The invention relates to a quick coupling for connecting at least two pressurized lines to a first coupling part that is connectable to a second coupling part so as to be pressure-proof.
Quick couplings (rapid action couplings) of the generic type are well known. They are used to connect pressurised medium-conducting lines, and are used with liquids, for example with hydraulic oils, gases and other suitable media. Normally such quick couplings comprise two coupling parts, wherein a first coupling part is a plug-in part and a second coupling part is a socket part. To bring about coupling, the plug-in part can be pushed into the socket part. The generic quick coupling is also used to connect lines that are subjected to high media pressures. In such cases the connection has to be established one time under pressure in the socket part and another time under pressure in the plug-in part of the coupling. The connection can also be made with both coupling parts being either in the pressurised state or in the non-pressurised state.
In the case of quick couplings for high media pressures for example from 20 to 50 MPa in one of the two, or in both, coupling parts, pressure reduction elements are known for easier handling during the coupling process. By means of such pressure reduction elements it is possible to reduce the pressure in the coupling part by draining a small quantity of the medium to the face of the coupling part. Connection of the coupling parts of the quick coupling is facilitated in this way. Arranging pressure reduction elements in both coupling parts is also known.
From DE 41 01 001 A1 a coupling device is known in which a pressure reduction element is arranged and operated in the interior of at least one coupling part when the plug-in part is connected to a socket part. The pressure reduction element comprises a drain channel for the media pressure and a shut-off element which is arranged in the pressure reduction element and which can be operated by way of an operating element. When the pressure reduction element is operated the chambers of the coupling parts connected to said pressure reduction element form communicating vessels, as a result of which pressure equalisation takes place and the coupling can be closed with little physical effort.
Quick couplings are frequently associated with a problem in that the pressure reduction elements located in the coupling parts are of complex construction. Furthermore, impurities in the medium can lead to the pressure reduction elements clogging up and rendering the quick couplings heavy to operate. There is a further disadvantage in that depending on the type of the quick coupling the plug-in part or the socket part or both coupling parts have to comprise the complex pressure reduction elements.
To overcome this problem, quick couplings comprising two coupling parts, namely the plug-in part and the socket part, are known from DE 102 17 922 A1, which however comprise other pressure reduction options for the coupling process. In these quick couplings several plug-in parts of several pressurised lines are arranged in one connection block. The several socket parts which face the plug-in parts are accommodated in an additional connection block. A stud, which is centrally arranged in the connection block between the lines, is faced by a control piston between the socket parts, which control piston is centrally arranged in the connection block. The socket parts are connected to a pressure relief device. In an additional connection block (plug-in part) the elements of the pressure relief device are connected to the connection block (socket part).
Pressure-relief valve systems are integrated in the pressure relief device. Each line has its own pressure-relief valve system. The existing pressure-relief valve systems are connected to a shared pressure relief line by way of a pressure relief chamber. However, this arrangement, in which each line has its own pressure-relief valve system, is an expensive solution.
Furthermore, in most of the known quick couplings securing the coupling parts in relation to each other is problematic. Since quick couplings are also used in a very high-pressure range from 20 to 50 MPa, the requirements for firm connection between the coupling parts are very demanding. Apart from the actual design of the quick coupling, which in itself is very expensive and complicated, there is thus an additional need to integrate the locking elements in the housing of the quick coupling.
From DE 41 01 001 A1 locking elements such as clamp-type actuating springs and clamp-type ball fittings are known. These locking elements must be made to close tolerances to achieve a secure connection of the parts during the coupling action. The complex design and exacting requirements relating to the precision of the coupling part and to the additional locking parts pose considerable problems.
It is thus the object of the invention to provide a quick coupling of the generic type which in an easy way supports simple coupling while overcoming the above-mentioned disadvantages in all pressure ranges.